The process of implanatation of the fertalized human embryo (the zygote) does not occur when the woman is taking birth control pills or when there is an IUD present in the uterus. Both change the lining of the uterus so it is inreceptive to the attachment of the zygote. This is why Roman Catholics, who believe life begins at inception, have not been receptive to birth control techniques.
The question about implantation makes me wonder if people paid attention to what was being taught in their sex education classes.
both computer and operator error: inception = conception.
We know that both the pill and the IUD prevent the sperm from reaching the oocyte - anyone who practices natural family planning understands the significance of the thickened cervical mucus due to the progesterone surge after ovulation.
Reference: experiments done by Croxatto and by Durand.
However, I don’t advise IUD’s because they can also interfere with implantation and with development of the child.
(And, BTW, The women who take progesterone to support early pregnancies understand how progesterone works to improve the chances of implantation and continuation of the pregnancy.)